What would you suggest University of British Columbia management do to prevent others from leaving?

Overhaul food services management. Remove bullies. Stop favorites.

First of all the union should be supporting new employees more than they support older employees. We are all paying the same dues.
Complaints should be taken serious by HR and some type of remediation could take place to resolved disagreements between staff.
There are no rules in place on how a manager is to treat a subordinate. Managers abuse their authority and seniority in the workplace.